Housekeeper, Albert Gomez, on Tuesday August 28, 2012, sprays the floors of a tent cabin with a bleach mixture to prevent the possible spread of viruses at Curry Village at Yosemite National Park. Four people have been infected with the hantavirus, two of which have died while staying at the Curry Village tent cabins at Yosemite National Park in California.

Photo: Michael Macor, The Chronicle

Housekeeper, Albert Gomez, on Tuesday August 28, 2012, sprays the...

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Glenn Dean, a National Parks Occupational Safety and Health Specialist inspects tent cabins for mice entry points at Curry Village at Yosemite National Park on Tuesday August 28, 2012. Four people have been infected with the hantavirus, two of which have died while staying at the Curry Village tent cabins at Yosemite National Park in California.

State public health scientists have recommended twice in the past five years that Yosemite National Park authorities educate visitors about hantavirus, a rare disease linked to the deaths of two park visitors this summer - but park officials did not warn tourists until after the disease showed up in recent weeks.

Inspectors with the state Department of Public Health urged Yosemite officials in 2010 to educate those staying in tent cabins about the often-fatal disease. The inspectors made the recommendation after a 54-year-old visitor fell ill with hantavirus after a stay in a tent cabin at Tuolumne Meadows similar to the ones at Curry Village, where this year's victims apparently caught the disease.

"Provide each cabin with information" on hantavirus, the health agency said in a report called a risk assessment. "Together with the bear safety guidance, guests should be advised to minimize contact with rodents and to report signs of rodent intrusion (e.g., droppings, chewed items) to Tuolumne Meadows Lodge management."

It was the second time the state had made such a recommendation. In 2007, state vector-borne disease scientists advised Yosemite to "minimize risk to staff and visitors through an active prevention program that includes the following elements: education ... and active rodent removal within buildings and developed areas."

Tuning out

Capt. Charles Higgins, who has been director of the public health office for the National Park Service for eight years, said he didn't know of any efforts to warn tent-cabin renters about the disease before this summer's outbreak. He said the risk of disease transmission was thought to be low, but that the potential for guests to tune out an overabundance of warnings was high.

"That's always a dilemma because people have message fatigue," Higgins said. "Their eyes glaze over, they quit paying attention to messaging. It's a little bit of an art form on when to (issue warnings) and how to approach it."

Yosemite ranger Kristen Kosick said park staffers were trained about the risks of hantavirus.

"There'd been no outreach to visitors, but there had been to staff," Kosick said. "It's a general virus people should be aware of if they're in Western states and outdoors."

Kari Cobb, a park ranger and spokeswoman, said education on the disease is mandatory for employees who open up closed buildings after each year's thaw.

Visitors alerted

Park authorities say they are notifying about 2,700 people that they could have been exposed to the mouse-spread disease after staying in Curry Village tent cabins. Two people who stayed in the cabins in June have died. Four other cases of infection have been confirmed by the California Department of Health.

Giorgio Cosentino, an East Bay microbiologist, said one of the dead victims was a physician and a family friend. He said that even though the risk of hantavirus transmission is low, Yosemite should have warned visitors it existed.

"If you can't get rid of the rodent problem completely and you can't get rid of the virus completely, the safety net includes educating visitors so if they do become ill, they can get to a hospital sooner," Cosentino said. "That still doesn't guarantee that they'll live, but chances of survival are better if you get to a hospital sooner."

No cure

Hantavirus is spread by white-bellied deer mice and is most readily caught by inhaling mouse feces or urine dust. Symptoms begin one to six weeks after exposure and include fever, headache, muscle aches and, later, difficulty breathing. The disease kills more than a third of those infected, and there is no cure.

Since 1993, 60 cases have been reported in California, including 2000 and 2010 cases at Yosemite, and 587 nationwide, according to the California Department of Public Health.

Vicki Kramer, chief of the state agency's vector-borne disease section, noted that Yosemite is run by the federal government. "Certainly we can make recommendations," she said, "but it's up to Yosemite on what further steps to take."

Mouse-friendly

After the 2010 case, state Department of Public Health scientists found rodent hiding places in the Tuolumne Meadows tent-cabin area, such as stacked firewood, and deficiencies that would allow mice access to cabins.

Kosick, the Yosemite ranger, said park staff and concessionaires were given a 12-page directive that details warning signs of the disease, precautionary measures to prevent infection and protective gear to wear.

Kosick said park staffers are now handing pamphlets to visitors informing them about hantavirus and expect to do so indefinitely.